'It has been consistently demonstrated that individuals who suffer from schizophrenia and related disorders are more likely than the general population to reside in socioeconomically deprived neighbourhoods. The social drift hypothesis suggests that the clinical features of psychotic disorders contribute to a gradual downward socioeconomic trajectory. Our understanding of the underlying causes linking schizophrenia to later deprivation remains, however, limited.
'We addressed this by combining nationwide Swedish data on nearly 760,000 sibling pairs (twins, non-twin full-siblings and half-siblings) with quantitative genetic models. We found that neighbourhood deprivation in adulthood was considerably heritable with genetic factors explaining 65% of the risk differences in the population. Importantly, we found that that the excess risk of residing in deprived neighbourhoods in schizophrenia was entirely due to genetic confounding, or overlapping genetic influences between schizophrenia and neighbourhood deprivation. In complementary sub-studies, we replicated these findings using sub-clinical measures of psychotic experiences and, for the first time, we estimated a statistically significant association between polygenic risk scores for schizophrenia derived from DNA data and neighbourhood deprivation in late adulthood among nonclinical participants.
'These findings support a genetic selection mechanism, where genetic liability for schizophrenia also predicts later deprivation. This implies that previous studies may have overemphasised the relative importance of environmental influences in the social drift of schizophrenia patients.'
Words: Amir Sariaslan
Read the full paper in Translational Psychiatry
Read the paper cited in Scientific American: 'Does City Life Pose a Risk to Mental Health?'